The present invention relates to wood framing systems for residential and light commercial buildings. More specifically, the present invention is concerned with a framing system and component designs with built-in thermal breaks throughout the entire external walls.
Standard construction today uses either 2×4 or 2×6 solid lumber generally spaced 16″ on center. Where energy conservation is a concern, most builders frame an exterior wall with 2×6's. Up to 30 percent of the exterior wall (studs, top and bottom plates, cripple studs, window/door jams and headers) is solid wood framing. Thermal bridges are points in the wall that allow heat and cold conduction to occur. Heat and cold follow the path of least resistance—through thermals bridges of solid wood across a temperature differential wherein the heat or cold is not interrupted by thermal insulation. The more volume of solid wood in a wall also reduces available insulation space, and further, the thermal efficiency of the wall suffers and the R value (resistance to conductive heat flow) decreases.
The most common way to minimize thermal bridging is to wrap the entire exterior of the building in rigid insulation to minimize heat loss and cold from entering the building. This effort significantly increases materials, carbon footprint and labor costs and can be undesirable in increasing the thickness of the building walls with non-structural materials.
Attempts have been made to construct framing systems with built in thermal breaks with the use of dimensional lumber (2×4, 2×6, 2×8, 2×10 and 2×12). Such efforts require extensive labor and materials costs and have not resulted in effective thermal breaks throughout the whole wall, corners and building envelope structure.
There is a need to design a framing system with complete thermal breaks throughout the walls, corners and building structure made of non-dimensional lumber with rigid insulation that has increased strength, more surface area for building materials to be fastened to, uses less lumber, has more space for insulation to greatly increase thermal efficiencies.
To understand benefits of the present invention, one must have an understanding of the standard or conventional wood framed building. A 960 square feet building 10 is used here illustratively.
Referring to prior art FIGS. 1 through 5, the top sectional plan view and wall constructions of the standard 960 square feet building 10 maybe understood. The actual face of a piece of dimensional lumber (2×4, 2×6, 2×8, 2×10 and 2×12) is actually only 1⅜″ because the edges are rounded to minimize splintering of the wood for the sake of the carpenter to avoid slivers.
Sectionally from the exterior surface to the interior surface typically are located siding 12, exterior air film 14, oriented strand board (OSB) plywood sheathing, fiberglass batt insulation 16 (or blown-in or sprayed-in insulation), 2×6 wall studs 22 16″ on center, interior air film 24 and gypsum board 26. Headers 30 typically comprises two 2×6 with rigid foam insulation 31.
From the plan view (FIG. 1) the standard building R values: through the 2×6 studs 22 is 9.16; through the header 30 with foam insulation 31 is 15.285; average through the pocket corner 48 is 11.63; and through the insulated wall portion is 21.28. This standard building requires 109 2×6 vertically oriented 2×6 studs to be compared later to the thermal break or Tstud design and framing system of the present invention.
Prior art FIGS. 2 through 5 show the top plan view of the prior art standard 960 square feet building, the vertical wall construction of window back wall 38, the vertical wall construction of door front wall 40 and the vertical wall construction of side walls 42. The walls begin with 2×6 top and bottom plates 35 and 36, 2×6 wall studs, headers 30, window sills 32 and cripple studs 34 for adjacent windows 44, door 46, lower sills 32 and above headers 30. This standard building construction has 109 stud thermal bridges.
The standard pocket corner 48 is clearly depicted in FIG. 1 and is constructed of three 2×6's studs 50 built in a U shaped plus one side 2×6 stud 52. Insulation 54 is typically filled into its cavity.